search functions for filtering datasets by metadata

[HeatherSavoy-USDA]

The API lets you query a list of all datasets and then only metadata by individual datasets. It would be useful to provide a user function to obtain multiple datasets' metadata.

If the user supplies dataset names (support approximate matches), we could do individual metadata requests per dataset. But if we want to allow the user to filter by metadata (e.g. includes a precipitation variable), we'd have to request ALL metadata then filter. Maybe the results can be cached for like a day or if the user forces an update. How much filtering do we do in the function vs just providing all the info to the user for them to filter? We should return as much as they want but make it a format to easily manipulate.

[HeatherSavoy-USDA]

The cached entire metadata might be useful for error checking before sending the API bad requests.